phy: phy-mtk-tphy: add a new reference clock

Usually the digital and analog phys use the same reference clock,
but some platforms have two separate reference clocks for each of
them, so add another optional clock to support them.
In order to keep the clock names consistent with PHY IP's, change
the da_ref for analog phy and ref clock for digital phy.

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
diff --git a/drivers/phy/phy-mtk-tphy.c b/drivers/phy/phy-mtk-tphy.c
index 20167fe..81525a4 100644
--- a/drivers/phy/phy-mtk-tphy.c
+++ b/drivers/phy/phy-mtk-tphy.c
@@ -199,8 +199,8 @@
 		struct u3phy_banks u3_banks;
 	};
 
-	/* reference clock of anolog phy */
-	struct clk ref_clk;
+	struct clk ref_clk;	/* reference clock of (digital) phy */
+	struct clk da_ref_clk;	/* reference clock of analog phy */
 	u32 index;
 	u32 type;
 };
@@ -450,8 +450,17 @@
 	int ret;
 
 	ret = clk_enable(&instance->ref_clk);
-	if (ret)
+	if (ret < 0) {
+		dev_err(tphy->dev, "failed to enable ref_clk\n");
 		return ret;
+	}
+
+	ret = clk_enable(&instance->da_ref_clk);
+	if (ret < 0) {
+		dev_err(tphy->dev, "failed to enable da_ref_clk %d\n", ret);
+		clk_disable(&instance->ref_clk);
+		return ret;
+	}
 
 	switch (instance->type) {
 	case PHY_TYPE_USB2:
@@ -502,6 +511,7 @@
 	struct mtk_tphy *tphy = dev_get_priv(phy->dev);
 	struct mtk_phy_instance *instance = tphy->phys[phy->id];
 
+	clk_disable(&instance->da_ref_clk);
 	clk_disable(&instance->ref_clk);
 
 	return 0;
@@ -611,6 +621,11 @@
 					     &instance->ref_clk);
 		if (err)
 			return err;
+
+		err = clk_get_optional_nodev(subnode, "da_ref",
+					     &instance->da_ref_clk);
+		if (err)
+			return err;
 	}
 
 	return 0;